1. Field of the Invention
The present invention relates to a recording apparatus to produce an image on a recording medium being attached onto a recording medium fixing member, more specifically an adhered foreign material removal method or device therefor, and further a method to prevent the position dislocation, separation and film peeling of the recording medium due to the cleaning motion.
2. Description of the Related Art
In the recording of an image or character, there is a recording method by which an image receiving sheet which is a recording medium, and a transfer sheet which is a recording medium in the same manner, are superimposed and fixed on the recording medium fixing member(drum) and exposed by the laser. In this recording medium, one kind of image receiving sheet and a plurality of kinds of transfer sheets such as K (black), C (cyan), M (magenta), Y (yellow), are used. These recording media are set in a cassette for a recording medium of the recording apparatus in a reversal order to the recording order. Accordingly, in the cassette, from the upper layer, the image receiving sheet, and a plurality of recording media in the order of K, C, M, Y, are set in the laminated condition. In this connection, when a plurality of sets of the recording medium are set, these operations are repeated and the recording media are set.
In such the manner, a cassette 103 in which the recording media 101 are accommodated in recording order, is installed in a recording apparatus 105 as shown in FIG. 2. A pickup mechanism 107 is provided in the recording apparatus 105, and the pickup mechanism 107 has a function by which only one sheet of the recording medium 101 of the uppermost layer is picked up from the inside of the cassette 103 by, for example, rubber roller or suction absorption mechanism. By this pickup mechanism 107, after the recording medium 101 whose only one sheet is picked up passes through a conveying mechanism in which a guide plate, not shown, or roller is used, it is fixed on a drum 109 for recording.
As shown in FIG. 3, in the recording apparatus 105, a recording head 111 to conduct, for example, the laser exposure is provided, and the recording head 111 is reciprocally moved in a parallel direction to the rotation axis of the drum 109. The laser light Lb is emitted from the recording head 111, and irradiated as a plurality of spots. In this recording method, the rotation direction of the drum 109 is a main scanning direction, and the movement direction of the recording head 111 is a sub scanning direction. Accordingly, when the rotation movement of the drum 109 and the linear movement of the recording head 111 are combined, the spot scans on the transfer sheet, and a desired image is transferred onto the image receiving sheet.
When the recording apparatus 105 is operated, initially, the image receiving sheet is supplied and conveyed to the drum 109. At this time, the image receiving layer of the image receiving sheet is fixed so as to face the outside of the drum 109. Next, the recording apparatus 105 supplies and conveys a K color transfer sheet onto the image receiving sheet on the drum 109. In this case, the toner layer of the transfer sheet is fixed so as to face the image receiving layer of the image receiving sheet. That is, the image receiving layer of the image receiving sheet and the toner layer of the transfer sheet are superimposed. Next, the recording apparatus 105 records on the recording medium 101 fixed on the drum 109 by the recording head 111. After the recording by the K-color data is completed, only the K-color transfer sheet is peeled off from the drum 109, and delivered to the outside of the recording apparatus 105. When these supplying, recording, and delivering operations are conducted for the C, M, Y-color transfer sheets in the same manner, a desired color image is transferred onto the image receiving sheet.
In this connection, onto the drum of the recording apparatus described above, in order to avoid the image defects due to undulations of the drum surface (cutting flaw at the time of drum processing, cutting streak, groove or hole of the recording medium fixing release mechanism), or to enable to cope with each kind of sizes of recording medium, there is a case where a flexible plate (plate) is attached. In such the recording apparatus, the recording defects due to the adherence of the foreign material onto the flexible plate becomes a problem. The recording defects due to the adherence of the foreign material are largely divided into two kinds. One is the recording defect (generation of so-called [image reversing]) in the case where the foreign material on the flexible plate is adhered onto the image receiving sheet. Another one is the recording defect (generation of so-called [ring unevenness]) in the case where the foreign material is adhered onto the flexible plate.
The image reversing is generated due to the generation of the poor close contact of the transfer sheet with the image receiving sheet by the foreign material when the foreign material exists on the image receiving sheet. Further, the ring unevenness is generated when the foreign material exists on the flexible plate. That is, in the central portion in which the foreign material exists, although the transfer sheet and the image receiving sheet are closely contacted with each other, in its periphery, a gap is formed ring-like between the transfer sheet and the image receiving sheet, therefore, the transferring can not be performed in this gap, and the white un-transferred portion is generated ring-like around the foreign material. Further, due to the foreign material adhered on the flexible plate, the position dislocation is generated in the perpendicular direction to the rotation axis of the drum, and the focal point of the laser light for recording is shifted, and the sufficient energy density can not be obtained, and there is a case where the thinning of the image or lowering of the density is generated, and the image unevenness is generated.
Further, in the conventional apparatus, as described above, although the foreign material adhered onto the recording medium during the apparatus operation can be removed, the foreign material adhered and piled onto the recording medium conveying means such as the rotating drum for the recording or nip roller in the condition that the recording medium is not conveyed such as the case where the apparatus is not used, can not be removed. Therefore, specifically, the foreign material is adhered onto the image receiving sheet conveyed just after the power supply of the apparatus is turned on, and the image defect is generated.
Next, after these recording media are supplied to a supply tray, the uppermost one sheet is taken out by a pick-up roller, and conveyed to the rotating drum for the recording position by a conveying roller (nip roller) arranged on an intermediate route of a conveying path, and wound around the drum surface and fixed. In this manner, on the recording medium conveying path in the recording apparatus, several conveying rollers are arranged, and by these conveying rollers, the recording medium is conveyed at a predetermined timing.
In these conveying rollers, when any one roller is an adhesive roller, there is a case where the conveyance and cleaning effects are provided together, or a cleaning roller (formed of the adhesive roller) for the purpose of foreign material removal is provided separately from the conveying roller. When the adhesive roller is provided, the removal of the foreign material adhered onto the recording material and removal of the foreign material adhered during the recording medium conveyance can be conducted. Further, when the cleaning roller is arranged so that it can come into contact with the rotating drum for the recording, the removal of the foreign material adhered onto the rotating drum for the recording, and the removal of the foreign material adhered onto the recording medium during the supply and conveyance of the recording medium to the rotating drum for the recording, or the removal of the foreign material adhered onto the recording medium during the delivery conveyance of the recording medium from the rotating drum for the recording, can be conducted.
For the pick-up roller, conveying roller, and cleaning roller used in the conventional recording apparatus, generally, a roller of straight shape in which the diameter of the roller is constant along the whole width direction, is used. In this roller of straight shape, when the roller is brought into contact with the other material by only self weight of the roller, the contact can be evenly conducted along the whole width direction of the roller, however, when, as the nip roller 370 shown in FIG. 35(a), it structures the roller pair, and nips with a predetermined pressing force between each of rollers, because the roller is bent, there is a tendency that the pressing force at the central portion in the width direction of the roller is smaller, and in the worst condition, there is a case that the pressing force at the central portion can not be obtained. Further, even when the nip roller is not structured, as shown in FIG. 35(b), for example, a drive mechanism 372 such as air piston is provided on both ends of the roller, and the roller 374 can be pressed onto the opposite surface. In the same manner also in this case, there is a tendency that the pressing force at the central portion in the width direction becomes small by the bend generated in the roller 374.
In this connection, the recording medium conveyed in the recording apparatus makes, when it is wound around the rotating drum for the recording and fixed, the image receiving sheet and the color material sheet superimposed, and closely contacted with each other by the vacuum suction or pressure roller. In the degree of the close contact, it is large at the edge portion of the sheet, and at almost the central portion of the sheet, because the air flow resistance becomes large, the suction easily becomes insufficient, and there is a case where the close contact is not conducted sufficiently. In this condition, when the foreign material exists on the sheet, the image defect due to the foreign material is particularly easily conspicuous at the central portion in the width direction. Therefore, it is necessary that the foreign material removal at the central portion in the width direction is assuredly conducted.
Accordingly, when the recording medium is pressed by the pressure roller (for example, a laminate roller, cleaning roller, squeeze roller) which can be brought into contact with the surface of the rotating roller for the recording, from the above reason, the pressing force at the central portion in the width direction of the roller becomes weak, and there is a problem that the degree of the close contact of the recording medium is lowered.
Further, when the material used for the adhesive roller is an adhesive rubber material or adhesive substance, because there is a case where the adhesive strength is lowered by the natural aging, therefore, after the production of the adhesive roller, the adhesive strength is lowered after about 302-303 months, and the ability to remove the foreign material on the recording medium is lowered. As the result, there is a problem that a portion on which a desired image is not recorded is generated on the recording image, and the image defect is generated.
In the related cleaning method of the recording medium, one end portion of the recording medium set on the rotating drum for the recording is a cleaning start point, and the other end portion is a cleaning end point, and a cleaning roller is brought into contact with the recording medium and the cleaning is continuously conducted. In FIG. 43, the conventional cleaning procedure is shown. As shown in FIG. 43(a), when a cleaning roller 450 is brought into contact with the end portion 1a of the recording medium or the drum surface on this side of the end portion 1a, and the rotating drum for the recording 412 is rotated, at the end portion 1a of the recording medium, because there is a tendency that the suction force to the rotating drum for the recording 412 is lowered, the adhesive strength of the cleaning roller 450 is sometimes relatively larger than the vacuum suction force from the rotating drum for the recording 412. In this case, as shown in FIG. 43(b), the end portion 1a of the recording medium 401 is wound around the cleaning roller 450. Further, in the same manner, when the cleaning roller 450 which is brought into contact with the recording medium 401 is vertically separated from the recording medium 401 at the end portion 1a, there is a possibility that the recording medium 401 is pulled up and a portion of the end portion 1a is separated from the rotating drum for the recording 412, or the film of the recording medium 401 is peeled off.
Therefore, the adhesive strength of the cleaning roller 450 is previously appropriately designed corresponding to the characteristic of the recording medium 401, and when it is necessary that the applicable kind of the recording medium 401 is enlarged or the foreign material is removed more strongly, there is sometimes a case in which the cleaning roller formed of the material having the strong adhesive strength is used, or the rubber roller whose rubber hardness is small and whose flexibility is high is used. In this case, because the adhesion property of the cleaning roller 450 is strong, problems in which the position dislocation is generated in the recording medium 401 on the rotating drum for the recording 412, or the suction leakage for the recording medium fixing is increased by this position dislocation, and the recording medium 401 is separated from the rotating drum for the recording 412, or the film (the image receiving layer 2c of the image receiving sheet 402 or cushion layer 2b) of the recording medium 401 is peeled off, are generated.
Further, as a conveying mechanism of the sheets used for the above related arts, there is a mechanism in which the image receiving sheet or transfer sheet is previously cut into a predetermined dimensions, and the image receiving sheet and the transfer sheet of a plurality of colors (or single color) are accommodated in a cassette of the recording apparatus, and at the time of recording, these sheets are successively conveyed, or on the one hand, a mechanism in which a roll for the image receiving sheet and a plurality of rolls corresponding to the plurality of colors of the transfer sheet are provided in the recording apparatus, and at the time of recording, these sheets are cut into predetermined dimensions by respective rolls, and conveyed to the rotating drum for the recording.
The image receiving sheet conveyed by the above mechanism, after it is wound around the rotating drum for the recording with the image receiving surface facing upward and fixed, the transfer sheet is conveyed to the rotating drum for the recording and the toner layer of the transfer sheet is superimposed on the image receiving layer of the image receiving sheet, and wound around the rotating drum for the recording. In this manner, onto the image receiving sheet and the transfer sheet which are superimposed on each other on the rotating drum for the recording, the laser exposure is conducted by the recording head. In the recording by the laser exposure, the recording and transferring is conducted when the rotating drum for the recording is rotated in the circumference direction of the drum, and the recording head is reciprocally moved in the rotating axis direction of the rotating drum for the recording. Then, the transfer sheet onto which the first transfer is conducted, is peeled off from the image receiving sheet, and after it is delivered, the next transfer sheet is conveyed in such a manner that it is superimposed on the image receiving sheet on the rotating drum for the recording, and fixed, and after that, it is transferred onto the image receiving sheet. After the transfer process onto the image receiving sheet is conducted for a plurality of times (a plurality of colors), when the image receiving sheet onto which the transfer is conducted, is transferred onto the another sheet, a desired color recording is conducted.
In this connection, there is sometimes a case in which the foreign material such as dirt or dust is adhered onto the surface of the recording medium supply section, recording medium conveying section, recording section in the recording apparatus, or recording medium during conveying by the static electrical force, and when recording is conducted without removing these foreign material, it becomes a cause by which the image defect such as the [image reversing] due to the existence of the foreign material between the image receiving sheet and the transfer sheet, or the [ring unevenness] due to the mixing of the foreign material between the drum for the recording and the image receiving sheet or between the transfer sheet and the roller, is caused. Therefore, the adhesive roller (cleaning roller) using the adhesive rubber is arranged in order to remove the foreign material adhered onto the surface of the conveying path of the recording material or recording section in the recording apparatus, and the adhesive roller is pressed on the surface which is the object of the foreign material removal, periodically or in need, and the foreign material is removed, and the system is made so that the good recording condition is always maintained.
However, recently, there is a system in which the pressing of the adhesive roller onto the surface which is the object of the foreign material removal is conducted by a movement apparatus such as an air cylinder, and at the time of requirement or periodically, the adhesive roller is automatically moved onto the objective surface of the foreign material removal, and the foreign material of the surface is removed. However, in the adhesive roller provided with the movement mechanism, the control of the pressing force onto the foreign material removal surface, that is, the minute amount control of the movement amount of the movement mechanism is difficult, and there is a case in which a poor foreign material removal due to insufficient pressing force onto the foreign material removal surface is generated, or the position dislocation of the image receiving sheet or transfer sheet fixed onto the rotating drum for the recording due to the increase of the adhesive strength by the excessive pressing force is generated. Further, due to the excess of the pressing force onto the sheet surface of the adhesive roller, the adherence peeling of the surface layer such as the image receiving layer of the image receiving sheet or cushion layer, or the adherence peeling of the surface layer such as the color material layer of the transfer sheet or photo thermal conversion layer is frequently generated. Then, every time when the poor recording due to the adherence peeling of the image receiving sheet or transfer sheet is generated, it is necessary that the recording apparatus is stopped, and the operation such as the taking out of the poor sheet or the reset of the image receiving sheet or transfer sheet is conducted, thereby, the transfer recording efficiency of the recording apparatus is not always good, and the improvement of the foreign material removal mechanism using the adhesive roller is required.